Implement java bindings for custom baseline function

Summary: Implement java bindings for custom baseline function

Differential Revision: D4392516

fbshipit-source-id: 39cf6066f8e5982268becd87e54c9ab51fbf7a90

java/com/facebook/yoga/YogaBaselineFunction.java

@@ -0,0 +1,22 @@
+/**
+ * Copyright (c) 2014-present, Facebook, Inc.
+ * All rights reserved.
+ *
+ * This source code is licensed under the BSD-style license found in the
+ * LICENSE file in the root directory of this source tree. An additional grant
+ * of patent rights can be found in the PATENTS file in the same directory.
+ */
+
+package com.facebook.yoga;
+
+import com.facebook.proguard.annotations.DoNotStrip;
+
+@DoNotStrip
+public interface YogaBaselineFunction {
+  /**
+   * Return the baseline of the node in pixels. When no baseline function is set the baseline
+   * default to the computed height of the node.
+   */
+  @DoNotStrip
+  float baseline(YogaNodeAPI node, float width, float height);
+}

java/com/facebook/yoga/YogaNode.java

@@ -52,6 +52,7 @@ public class YogaNode implements YogaNodeAPI<YogaNode> {
   private YogaNode mParent;
   private List<YogaNode> mChildren;
   private YogaMeasureFunction mMeasureFunction;
+  private YogaBaselineFunction mBaselineFunction;
   private long mNativePointer;
   private Object mData;
 
@@ -623,6 +624,18 @@ public class YogaNode implements YogaNodeAPI<YogaNode> {
           YogaMeasureMode.values()[heightMode]);
   }
 
+  private native void jni_YGNodeSetHasBaselineFunc(long nativePointer, boolean hasMeasureFunc);
+  @Override
+  public void setBaselineFunction(YogaBaselineFunction baselineFunction) {
+    mBaselineFunction = baselineFunction;
+    jni_YGNodeSetHasBaselineFunc(mNativePointer, baselineFunction != null);
+  }
+
+  @DoNotStrip
+  public final float baseline(float width, float height) {
+    return mBaselineFunction.baseline(this, width, height);
+  }
+
   @Override
   public boolean isMeasureDefined() {
     return mMeasureFunction != null;

java/com/facebook/yoga/YogaNodeAPI.java

@@ -18,6 +18,7 @@ public interface YogaNodeAPI<YogaNodeType extends YogaNodeAPI> {
   YogaNodeType getParent();
   int indexOf(YogaNodeType child);
   void setMeasureFunction(YogaMeasureFunction measureFunction);
+  void setBaselineFunction(YogaBaselineFunction measureFunction);
   boolean isMeasureDefined();
   void calculateLayout();
   boolean isDirty();

java/jni/YGJNI.cpp

@@ -63,6 +63,14 @@ static void YGPrint(YGNodeRef node) {
   }
 }
 
+static float YGJNIBaselineFunc(YGNodeRef node, float width, float height) {
+  if (auto obj = YGNodeJobject(node)->lockLocal()) {
+    return findClassLocal("com/facebook/yoga/YogaNode")->getMethod<jfloat(jfloat, jfloat)>("baseline")(obj, width, height);
+  } else {
+    return height;
+  }
+}
+
 static YGSize YGJNIMeasureFunc(YGNodeRef node,
                                float width,
                                YGMeasureMode widthMode,
@@ -203,6 +211,10 @@ void jni_YGNodeSetHasMeasureFunc(alias_ref<jobject>, jlong nativePointer, jboole
   YGNodeSetMeasureFunc(_jlong2YGNodeRef(nativePointer), hasMeasureFunc ? YGJNIMeasureFunc : NULL);
 }
 
+void jni_YGNodeSetHasBaselineFunc(alias_ref<jobject>, jlong nativePointer, jboolean hasBaselineFunc) {
+  YGNodeSetBaselineFunc(_jlong2YGNodeRef(nativePointer), hasBaselineFunc ? YGJNIBaselineFunc : NULL);
+}
+
 jboolean jni_YGNodeHasNewLayout(alias_ref<jobject>, jlong nativePointer) {
   return (jboolean) YGNodeGetHasNewLayout(_jlong2YGNodeRef(nativePointer));
 }
@@ -332,6 +344,7 @@ jint JNI_OnLoad(JavaVM *vm, void *) {
                         YGMakeNativeMethod(jni_YGNodeIsDirty),
                         YGMakeNativeMethod(jni_YGNodeMarkLayoutSeen),
                         YGMakeNativeMethod(jni_YGNodeSetHasMeasureFunc),
+                        YGMakeNativeMethod(jni_YGNodeSetHasBaselineFunc),
                         YGMakeNativeMethod(jni_YGNodeCopyStyle),
                         YGMakeNativeMethod(jni_YGNodeStyleGetDirection),
                         YGMakeNativeMethod(jni_YGNodeStyleSetDirection),

java/tests/com/facebook/yoga/YogaNodeTest.java

@@ -23,6 +23,35 @@ public class YogaNodeTest {
     assertEquals(refCount + 1, YogaNode.jni_YGNodeGetInstanceCount());
   }
 
+  @Test
+  public void testBaseline() {
+    final YogaNode root = new YogaNode();
+    root.setFlexDirection(YogaFlexDirection.ROW);
+    root.setAlignItems(YogaAlign.BASELINE);
+    root.setWidth(100);
+    root.setHeight(100);
+
+    final YogaNode child1 = new YogaNode();
+    child1.setWidth(40);
+    child1.setHeight(40);
+    root.addChildAt(child1, 0);
+
+    final YogaNode child2 = new YogaNode();
+    child2.setWidth(40);
+    child2.setHeight(40);
+    child2.setBaselineFunction(new YogaBaselineFunction() {
+        public float baseline(YogaNodeAPI node, float width, float height) {
+          return 0;
+        }
+    });
+    root.addChildAt(child2, 1);
+
+    root.calculateLayout();
+
+    assertEquals(0, (int) child1.getLayoutY());
+    assertEquals(40, (int) child2.getLayoutY());
+  }
+
   @Test
   public void testMeasure() {
     final YogaNode node = new YogaNode();